title: Changes in metabolic markers in insulin-producing β-cells during hypoxia-induced cell death as studied by NMR metabolomics.
abstract: This study was designed to investigate changes in the metabolites in the intracellular fluid of the pancreatic β-cell line INS-1 to identify potential early and late biomarkers for predicting hypoxia-induced cell death. INS-1 cells were incubated under normoxic conditions (95% air, 5% CO₂) or hypoxic conditions (1% O₂, 5% CO₂, 95% N₂) for 2, 4, 6, 12, or 24 h. The biological changes indicating the process of cell death were analyzed using the MTT assay, flow cytometry, Western blotting, and immunostaining. Changes in the metabolic profiles from cell lysates were identified using ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, and the spectra were analyzed by the multivariate model Orthogonal Projections to Latent Structure-Discriminant Analysis. Cell viability decreased approximately 40% after 12-24 h of hypoxia, coincident with a high level of cleaved caspase-3. A high level of HIF-1α was detected in the 12-24 h hypoxic conditions. The metabolite profiles were altered according to the degree of exposure to hypoxia. A spectral analysis showed significant differences in creatine-containing compounds at the early stage (2-6 h) and taurine-containing compounds at the late stage (12-24 h), with the detection of HIF-1α and cleaved caspase-3 in cells exposed to hypoxia compared to normoxia. Glycerophosphocholine decreased during the early stage hypoxia. The change in taurine- and creatine-containing compounds and choline species could be involved in the β-cell death process as inhibitors or activators of cell death. Our results imply that assessment by ¹H NMR spectroscopy would be a useful tool to predict the cell death process and to identify molecules regulating hypoxia-induced cell death mechanisms.
authors.affiliation: Department of Biomedical Science, College of Medicine, Medical Research Center, Seoul National University, 101 Daehangno, Jongnogu, Seoul 110-744, Korea.
authors.forename: Lianji
authors.initials: L
authors.lastname: Tian
authors.forename: Hoe Suk
authors.initials: HS
authors.lastname: Kim
authors.forename: Heyonjin
authors.initials: H
authors.lastname: Kim
authors.forename: Xing
authors.initials: X
authors.lastname: Jin
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Jung
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Park
authors.forename: Kyoung Won
authors.initials: KW
authors.lastname: Cho
authors.forename: Sunghyouk
authors.initials: S
authors.lastname: Park
authors.forename: Woo Kyung
authors.initials: WK
authors.lastname: Moon
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects*; D045744:Cell Line, Tumor; D016002:Discriminant Analysis; D015870:Gene Expression / Q000187:drug effects; D005997:Glycerylphosphorylcholine / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000096:biosynthesis; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways / Q000187:drug effects*; D055442:Metabolome / Q000235:genetics*; D010100:Oxygen / Q000494:pharmacology*; D051381:Rats
chemical_list: D015415:Biomarkers; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D005997:Glycerylphosphorylcholine; D053148:Caspase 3; D010100:Oxygen